Find a used XSi if you're interested in taking pictures a little bit faster, if not, get the XS. (says my photo buddy that works in a photo shop)
He says the screen on the XS is too small (2.5"), the processor is slower than the XSi, 2 less megapixels, etc.
http://usa.canon.com/cusa/consumer/p...01e0248003ce52